Most kinds of apparatus, such as e.g. a photographic camera, a processor for exposed materials, an optoelectronic scanner, a xerographic copier, or a thermal printer, are mounted within a generally rectangular housing, which may include a rectangular metal frame for supporting various parts of the apparatus.
In many of these apparatus, the metal frame is made up at least in part from panels and the mechanical geometry of the frame panels, especially the relative distance between them, is very important in order to guarantee that the apparatus be of good quality and operate reliably.
The frame of the apparatus thus has to be designed and manufactured to satisfy rather small and demanding tolerances, thereby minimizing the creation of disturbing gaps or separations between panels. In addition, the frame thus formed needs a geometry which requires no adjustment after assembly and which remains stable over time.